Catalytic para-xylene maximization: III. Hydroisomerization of meta-xylene on H-ZSM-5 catalysts containing different platinum contents
✍ Scribed by A K Aboul-Gheit; S M Abdel-Hamid; S Z Mohamed; D S El-Desouky
- Publisher
- Wiley (John Wiley & Sons)
- Year
- 1999
- Tongue
- English
- Weight
- 97 KB
- Volume
- 74
- Category
- Article
- ISSN
- 0268-2575
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✦ Synopsis
Hydroisomerization of meta-xylene was carried out using catalysts containing 0.15±0.60 wt% Pt on H-ZSM-5 zeolite, in a pulsed microreactor system connected to a gas chromatograph at a ¯ow of hydrogen of 20 cm 3 min À1 and temperatures of 275±500 °C. Increasing temperature, increased isomerization with low rates. Increasing Pt content of the catalyst, decreased hydrodealkylation considerably via masking strong acid sites as revealed by temperature programmed desorption of ammonia measurements. Formation of trimethylbenzenes was inhibited by Pt incorporation in the H-ZSM-5 zeolite. The activation energies obtained for meta-xylene hydroisomerization were relatively low (24.4±61.6 kJ mol À1 ) on all catalysts under study. Para-xylene yields in the xylenes mixture of product relative to the corresponding thermodynamic equilibrium values amount to about 0.8±0.9 at temperatures of 400±500 °C but were lower at lower temperatures.